I thought they get reimbursed from head office. No "profit" to be made. That's why some big jobs they have to get authorisation from head office before they will take it on. Could be wrong.
I remember taking my TE50 into a ford dealership once to get the clutch tuning fork fixed. I was expecting to pay, because I didn't buy it from that dealer, it was an 02 model and it was around 2007 from memory. After doing the job the dealer sent me on my way without charge. I asked why, he said he managed to get head office to approve it.
Unfortunately that dealership doesn't exist anymore.